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I  reproject  a dwg file  using reproject transformer  from a beijing datum to a WGS84 datum, I used  BURSA  approximations.I'm  sure the  seven  parameters  is correct because  I'v  verified  these in arcmap . I defined  the datum  and the coordinate system  like  below in mycoordsysdefs.fme 

 

 

#DATUM_DEF Beijing1954 \\

 

#   DESC_NM “LocalTranstoWGS84” \\

 

#   SOURCE “me” \\

 

#   ELLIPSOID KRASOV \\

 

#   USE BURSA \\

 

#   DELTA_X -1200.73773931196236 \\

 

#   DELTA_Y 270.135884745262 \\

 

#   DELTA_Z -870.732624966858 \\

 

#   BWSCALE 41.6212793541839  \\

 

#   ROT_X 0.345260849        \\

 

#   ROT_Y 4.031002029         \\

 

#   ROT_Z 0.280361064        

 

 

from the  name list  of  coordinate system gallery  ,I can saw the COORDINATE_SYSTEM_DEF  I defined ,but  the part  info  like this

 

 

ESRI WKT Description

GEOGCSF"Unknown",DATUMp"D_Unknown",SPHEROIDp"Unknown",6378137,298.257223563]],PRIMEMU"Greenwich",0],UNITk"Degree",0.017453292519943295]]

 

 

1. why the datum and GEOGCS is unknown in esri wkt description ?  I defined them  following the the syntax of definitions  in mycoordsysdefs.fme  .

 

2. the transform result  is out of position about 1 second.  why?

 

can anybody  help me ? thanks in advance.
Hi Alice, Maybe FME ignores the line that starts with # as a comment...
thank you reply 

 

in fact , At first  I put the definitions in  LocalCoordSysDefs.fme  without  #  , but  the result  is the same as above.

my  COORDINATE_SYSTEM_DEF  use  fme predefined  definition:  Bjing54.GK3d/CM-117E

from the  name list  of  coordinate system gallery  , the  definition of  Bjing54.GK3d/CM-117E  is as  below:

 

CS_NAME: Bjing54.GK3d/CM-117E

 

DESC_NM: Beijing 1954 / 3-degree Gauss-Kruger CM 117E

 

DT_NAME: Beijing1954

 

GROUP: ASIA

 

MAP_SCL: 1

 

PARM1: 117

 

PROJ: TM

 

QUAD: 1

 

SCL_RED: 1

 

SOURCE: EPSG, V6.6, 2436 UEPSG]

 

UNIT: Meter

 

X_OFF: 500000

 

ZERO_X: 0.0001

 

ZERO_Y: 0.0001

with the datum definition  and  CS  definition  , I don't  know how  to  fix  them  to  get  the  correct  transform  results .

Do you perhaps want to modify the definition of predefined datum named Beijin1954?

 

DATUM_DEF is used to define a new datum, I don't think it can modify predefined one. If you need to modify predefined datum, try defining DATUM_DEF with other name as a new datum.
thank you ,I'v  solved  the problem

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